A light emitting diode (LED) is a solid state device that converts electrical energy to light. Light is emitted from active layers of semiconductor material sandwiched between oppositely doped layers when a voltage is applied across the doped layers. In order to use an LED chip, the chip is typically enclosed in a package that focuses the light and that protects the chip from being damaged. The LED package typically includes contact points for electrically connecting the LED package to an external circuit or power source. Conventionally, LED chips are designed to be packaged either as a discrete light emitter or with a group of LED chips, e.g., in an array, to provide a light-emitting assembly.
Light-emitting assemblies comprising an array of LEDs include a number of LED dies that have been arranged in some predetermined fashion. It is known for conventional LED arrays to make use of one or more lenses for the purpose of both protecting the underling LED dies from being physically damaged, e.g., from contact with an external object, and for facilitating the emission of light from LEDs.
Existing lenses known in the art used with LED arrays are provided in the form of a pre-formed dome-shaped member that is sized and shaped to fit over a number of LED dies, and operate to provide a focused light emission. The lens is formed from glass or plastic, and includes attachment elements for providing a secure fit with a substrate. The lens can include a phosphor layer provided along a bottom surface adjacent the LED dies to provide a desired color light, e.g., white light.
Other light-emitting assemblies known in the art comprises lenses that are not provided as a pre-formed element, but that are provided in the form of a lens-forming material that is disposed over the LED dies, and that is shaped into a desired end-use configuration by cast molding, injection molding, or compression molding technique. In such conventional embodiments, the lens material is provided over an existing transparent protective layer disposed over the LED dies.
While light-emitting assemblies, comprising an array of LEDs, making use of LED dies and the above-noted lens constructions are somewhat useful in facilitating the emission of light from an array of LEDs, such light-emitting assemblies are limited in terms of their ability to provide an LED array having optimized packaging and lens construction to facilitate a light-emitting assembly construction capable of providing an optimized light output/transmission in a relatively small spatial package, thereby limiting potential end-use applications.
It is, therefore, desired that light-emitting assemblies, comprising an LED array formed from a plurality of LED dies, be developed in a manner having an optimized LED die spatial arrangement/packing density together with an optimized lens construction to provide an desired efficiently-packaged assembly having a high-light output/transmission when compared to conventional LED light-emitting assemblies. It is further desired that such assemblies be manufactured in a manner that is cost effective from a labor and/or a raw material perspective.